Projection display device

ABSTRACT

A projection display device which displays an image by projecting the image on a screen includes a laser light source  1  ( 1   a   , 1   b   , 1   c ) for emitting coherent light, a display device  3  for forming an image to be displayed on a screen  5  in an area illuminated by a luminous flux from the laser light source  1 , a first diffusion plate  14  for diffusing a luminous flux, and a second diffusion plate  15  for diffusing a luminous flux. The first diffusion plate  14  is provided in at least one of a conjugate position of the laser light source  1  or the vicinity of the conjugate position in the optical path of the optical system including the laser light source  1  through the screen  5 . The second diffusion plate  15  is provided in at least one of a conjugate position of the display device  3  or the vicinity of the conjugate position. At least one of the first diffusion plate  14  and the second diffusion plate  15  fluctuates perpendicularly to an optical axis.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Application No. 2009-105708, filed Apr. 23, 2009, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a projection display device such as aprojector etc., and more specifically to a projection display device fordisplaying an image by projecting the image on the screen etc. using adisplay device.

2. Description of the Related Art

Conventionally, a lamp light source such as an extra high pressuremercury lamp etc. has been used as a light source of a projectiondisplay device using a display device. Since such a lamplight source isshort-life, a maintenance operation such as exchanging a lamp isfrequently performed. In addition, when color images are displayed, itis necessary to provide, for example, an optical system for taking outred light, green light, and blue light from white light emitted from alamp light source. Therefore, the device configuration is complicatedand the light use efficiency is reduced.

On the other hand, although a projection display device using an LEDlight source has been proposed as a light source, it is low in the lightuse efficiency of the LED, thereby failing in attaining sufficientluminance on the displayed image.

Therefore, there has been an attempt to use a laser light source such asa semiconductor laser etc. as a light source of a projection displaydevice. Since the laser light source is longer-life than the lamp lightsource, maintaining operations are not required substantially. Inaddition, since laser light can be directly modulated depending on adisplayed image when the laser light source is used, the deviceconfiguration is simple and the light use efficiency can be improved.Furthermore, using a laser light source, a larger color reproductionarea can be obtained.

However, a laser light source has high coherence. Therefore, when alaser light source is used as a light source of a projection displaydevice, a pattern of high-contrast spots such as a speckle, specklenoise, speckle patterns, etc. (hereinafter referred to simply as“speckle”) is formed on the screen, thereby degrading the quality ofdisplayed images. Therefore, when a laser light source is used as alight source, it is important to reduce the speckle. Accordingly, thetechnology of reducing the speckle has been proposed in the followingvariations.

FIG. 1 is a schematic diagram of an operating illumination devicedisclosed by the patent document 1 (Japanese Laid-open PatentPublication No. 2005-301164). An illumination device 101 illustrated inFIG. 1 includes a laser light source 102, an electromagnet 103, anoscillation plate 104 and a diffusion plate 105. The oscillation plate104 is arranged opposite the electromagnet 103, and made by a magneticmaterial. The diffusion plate 105 is arranged at one end of theoscillation plate 104, and the laser light emitted from the laser lightsource 102 enters the diffusion plate 105. Then, the diffusion plate 105vibrates substantially perpendicularly to the laser light emissiondirection from laser light source 102 based on the operation of theelectromagnet 103, thereby reducing the speckle.

FIG. 2 is an explanatory view of the rough configuration of theprojector disclosed by the patent document 2 (Japanese Laid-open PatentPublication No. 2008-191279). A projector 111 illustrated in FIG. 2includes a light source (laser light source devices 112R, 112G, and112B), an intermediate image forming unit (first projection opticalsystem 113), an optical system for forming images (second projectionoptical system 114), and a diffusibility change unit (second diffusionelement 115, rotation drive unit 116). The light source emits a coherentlight. The intermediate image forming unit forms an intermediate imageusing the light from the light source. The optical system for formingimages forms an image on the display surface with the light from theintermediate image. The diffusibility change unit has a diffusingsurface in the position shifted from the intermediate image formingsurface on which an intermediate image is formed, and in the position ofthe optical path from the intermediate image forming unit to the opticalsystem for forming images including the intermediate image forming unit,and changes with time the diffusibility on the surface along thediffusing surface. Then, by the operation of the diffusibility changeunit, the speckle is to be reduced.

FIG. 3 is an explanatory view of the behavior etc. of the light in theoptical system of the projector disclosed by the patent document 3(Japanese Laid-open Patent Publication No. 2008-122823). The opticalsystem illustrated in FIG. 3 includes a light source unit 121 forproviding coherent light, a spatial light modulation device 123 formodulating the coherent light from the light source unit 121 dependingon the image signal and emitting the light from an emission unit 122,and a diffusion unit 124 for diffusing the light from the emission unit122 by a transmission. The diffusion unit 124 is provided and operatedin a position close to the emission unit 122 so that the speckle can bereduced.

FIG. 4 illustrates a coherent light display device having a diffusionelement as disclosed by the patent document 4 (Japanese Laid-open PatentPublication No. 06-208089). In the device illustrated in FIG. 4, thecoherent light is transmitted through a rotary diffusion element 132 toilluminating the spatial light modulator 131. The rotary diffusionelement 132 moves on a screen 133 at a speed at which an interferencepattern cannot be detected by human eyes, thereby reducing the speckle.

SUMMARY OF THE INVENTION

The projection display device according to an aspect of the presentinvention displays an image by projecting the image on a screen, andincludes at least one light source, a display device, a first diffusionunit, and a second diffusion unit. The light source emits coherentlight. The display device forms an image to be displayed on the screenin an area illuminated by a luminous flux from the light source. Thefirst diffusion unit diffuses the luminous flux. The second diffusionunit diffuses the luminous flux. The first diffusion unit is provided inat least one of the light source conjugate position and the vicinity ofthe position in the optical path of the optical system including thelight source through the screen. The second diffusion unit is providedin at least one of the display device conjugate position and thevicinity of the position in the optical path of the optical system. Atleast one of the first diffusion unit and the second diffusion unitfluctuates perpendicularly to the optical axis.

The projection display device according to another aspect of the presentinvention displays an image by projecting the image on a screen, andincludes at least one light source, an optical system for illumination,a display device, an optical system for projection, a first diffusionunit, a second diffusion unit, and a luminous flux intensity levelingunit. The light source emits coherent light. The optical system forillumination propagates the luminous flux emitted from the light sourceto a predetermined optical path and leads the flux towards the screen.The display device forms an image to be displayed on the screen in thearea illuminated by the luminous flux lead by the optical system forillumination. The optical system for projection scales up and projectson the screen the image formed in the illuminated area of the displaydevice. The first diffusion unit diffuses the luminous flux. The seconddiffusion unit diffuses the luminous flux. The luminous flux intensityleveling unit levels the intensity of the luminous flux. The luminousflux intensity leveling unit is provided in the optical system forillumination. The first diffusion unit is provided on the luminous fluxincident surface of the luminous flux intensity leveling unit or in thevicinity of the position. The second diffusion unit is provided on theluminous flux emission surface of the luminous flux intensity levelingunit or in the vicinity of the position. At least one of the firstdiffusion unit and the second diffusion unit fluctuates perpendicularlyto the optical axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an operating illumination devicedisclosed as a prior art;

FIG. 2 is an explanatory view of the rough configuration of theprojector disclosed as a prior art;

FIG. 3 is an explanatory view of the behavior etc. of the light in theoptical system of the projector disclosed as a prior art;

FIG. 4 illustrates a coherent light display device having a diffusionelement disclosed as a prior art;

FIG. 5 is a configuration before arranging a first diffusion plate and asecond diffusion plate in an example of a configuration of theprojection display device according to the embodiment 1;

FIG. 6 is the first configuration example of the projection displaydevice according to the embodiment 1;

FIG. 7 is the second configuration example of the projection displaydevice according to the embodiment 1;

FIG. 8 is the third configuration example of the projection displaydevice according to the embodiment 1;

FIG. 9 is the fourth configuration example of the projection displaydevice according to the embodiment 1;

FIG. 10 is the fifth configuration example of the projection displaydevice according to the embodiment 1;

FIG. 11 is a configuration before arranging a first diffusion plate anda second diffusion plate in an example of a configuration of theprojection display device according to the embodiment 2;

FIG. 12 is the first configuration example of the projection displaydevice according to the embodiment 2;

FIG. 13 is the second configuration example of the projection displaydevice according to the embodiment 2;

FIG. 14 is the third configuration example of the projection displaydevice according to the embodiment 2;

FIG. 15 is the fourth configuration example of the projection displaydevice according to the embodiment 2;

FIG. 16 is the fifth configuration example of the projection displaydevice according to the embodiment 2;

FIG. 17 is the sixth configuration example of the projection displaydevice according to the embodiment 2;

FIG. 18 is an example of a configuration of the projection displaydevice according to the embodiment 2 using a reflective display device;

FIG. 19 illustrates an ultrasonic motor fixed to an optical diffusiondevice via a frame; and

FIG. 20 is an explanatory view of another example of a fluctuating unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The embodiments of the present invention are described below withreference to the attached drawings.

Embodiment 1

The projection display device according to the embodiment 1 of thepresent invention displays an image by projecting the image on thescreen, and includes at least one light source, a display device, afirst diffusion plate (an example of the first diffusion unit) and asecond diffusion plate (an example of the second diffusion unit). Thelight source emits coherent light. The display device forms an image tobe displayed on the screen in an area illuminated by a luminous fluxfrom the light source. The first diffusion plate diffuses the luminousflux. The second diffusion plate diffuses the luminous flux. The firstdiffusion plate is provided in at least one of the light sourceconjugate position and the vicinity of the positions in the optical pathof the optical system including the light source through the screen. Thesecond diffusion plate is provided in at least one of the display deviceconjugate position and the vicinity of the positions in the optical pathof the optical system. At least one of the first diffusion plate and thesecond diffusion plate fluctuates perpendicularly to the optical axis.However, the fluctuating diffusion plate fluctuates perpendicularly tothe optical axis in the scope within the optical path of the opticalsystem.

FIG. 5 is a configuration before arranging the first diffusion plate andthe second diffusion plate in an example of a configuration of theprojection display device according to the present embodiment.

In the projection display device according to the present embodiment, asdescribed above, the first diffusion plate is provided in at least oneof the light source conjugate position and the vicinity of the positionsin the optical path of the optical system including the light sourcethrough the screen, and the second diffusion plate is provided in atleast one of the display device conjugate position and the vicinity ofthe positions in the optical path of the optical system. Therefore,there are a plurality of combinations of the arrangement positions ofthe first diffusion plate and the second diffusion plate. First, anexample of a configuration of the projection display device according tothe present embodiment excluding the first and second diffusion platesis described below with reference to FIG. 5.

As illustrated in FIG. 5, the projection display device according to thepresent embodiment excluding the first and second diffusion platesincludes three laser light sources 1 (1 a, 1 b, and 1 c), an opticalsystem for illumination 2, a display device 3, an optical system forprojection 4, and a screen 5.

Each of the three laser light sources 1 emits coherent light, forexample, as a red laser light source, a green laser light source, and ablue laser light source.

The optical system for illumination 2 propagates the luminous fluxemitted from each of the three laser light sources 1 into apredetermined optical path, leads the flux toward the screen 5, andincludes a relay lens 6, a relay lens 7, a relay lens 8, a stop unit 9,and a relay lens 10. The relay lens 6 also functions as a converginglens. In this optical system for illumination 2, the luminous fluxemitted from each of the three laser light sources 1 is led to thedisplay device 3 by the relay lens 6, the relay lens 7, the relay lens8, the stop unit 9, and the relay lens 10, and illuminates theillumination area of the display device 3.

The display device 3 forms an image to be displayed on the screen 5 inthe area illuminated by the luminous flux from the optical system forillumination 2 (laser light source 1). The display device 3 transmitsthe luminous flux illuminating the illuminated area to form on thescreen 5 the image formed in the illuminated area. The display device 3is a transmission display device using, for example, a liquid crystaldevice etc.

The optical system for projection 4 is an optical system for scaling upand projecting on the screen 5 the image formed in the illuminated areaof the display device 3, and includes a projection lens 11. In theoptical system for projection 4, the luminous flux is transmittedthrough the display device 3, scaled up by a projection lens 11, andprojected on the screen 5.

The three laser light sources 1 and the display device 3 are controlledby a control device not illustrated in the attached drawings.

With the above-mentioned configuration example, the positions (lightsource conjugate positions) having conjugate relationships with aposition 12 a of the luminous flux emission surface of the three laserlight sources 1 in the optical path of the optical System including thethree laser light sources 1 through the screen 5 are a convergingposition 12 b by the relay lens 6, a position 12 c of the stop unit 9,and a position 12 d of the entrance pupil of the projection lens 11(refer to the dotted line 12 in FIG. 5). The positions (display deviceconjugate positions) having conjugate relationships with a position 13 aof the luminous flux incident surface of the display device 3 in theoptical path of the optical system are a position 13 b between the relaylens 7 and the relay lens 8 and a position 13 c of the projectionsurface of the screen 5 (refer to the dotted line 13 in FIG. 5).

Therefore, in the projection display device according to the presentembodiment, the arrangement position of the first diffusion plate is oneof the position 12 a of the luminous flux emission surfaces of the threelaser light sources 1 or in the vicinity of the position, the convergingposition 12 b by the relay lens 6 or in the vicinity of the position,the position 12 c of the stop unit 9 or in the vicinity of the position,and the position 12 d of the entrance pupil of the projection lens 11 orin the vicinity of the position, in the optical path of the opticalsystem including the three laser light sources 1 through the screen 5.The arrangement position of the second diffusion plate is one of theposition 13 a of the luminous flux incident surface of the displaydevice 3 or in the vicinity of the position, the position 13 b betweenthe relay lens 7 and the relay lens 8 or in the vicinity of theposition, and the position 13 c of the projection surface of the screen5 or in the vicinity of the position, in the optical path of the opticalsystem including the three laser light sources 1 through the screen 5.

Thus, in the projection display device according to the presentembodiment, there are a plurality of combinations as the arrangementpositions of the first diffusion plate and the second diffusion plate,but five representative arrangement examples are described below.

In each arrangement example, both of the first diffusion plate and thesecond diffusion plate fluctuate perpendicularly to the optical axis,but the configuration in which one of the plates fluctuates can berealized. Each of the first diffusion plate and the second diffusionplate is provided with an ultrasonic motor as illustrated in FIG. 18 anddescribed later. The ultrasonic motor is an example of a unit forfluctuating a diffusion plate, and can fluctuate the diffusion plate byfinely oscillating a piezoelectric element included in the ultrasonicmotor. The ultrasonic motor for finely oscillating the piezoelectricelement is controlled by a control device for controlling the threelaser light sources 1 and the display device 3. In this case, theultrasonic motor is controlled so that the fluctuation speed of each ofthe first diffusion plate and the second diffusion plate can be, forexample, 2.0 mm/s or more.

FIG. 6 is the first configuration example of the projection displaydevice according to the present embodiment.

The first configuration example illustrated in FIG. 6 is an example ofarranging a first diffusion plate 14 in the converging position 12 b (orin the vicinity of the position) by the relay lens 6, and arranging asecond diffusion plate 15 in the position 13 c (or in the vicinity ofthe position) of the projection surface of the screen 5. According tothe present configuration example, the luminous flux converged by therelay lens 6 is diffused by the first diffusion plate 14 whichfluctuates perpendicularly to the optical axis (for example the verticaldirection indicated by the arrow A in FIG. 6). Furthermore, the luminousflux projected by the projection lens 11 is diffused by the seconddiffusion plate 15 which fluctuates perpendicularly to the optical axis(for example, the vertical direction indicated by the arrow B in FIG.6).

FIG. 7 is the second configuration example of the projection displaydevice according to the present embodiment.

The second configuration example illustrated in FIG. 7 is an example ofarranging the first diffusion plate 14 in the converging position 12 b(or in the vicinity of the position) by the relay lens 6, and arrangingthe second diffusion plate 15 in the position 13 a (or in the vicinityof the position) of the luminous flux incident surface of the displaydevice 3. According to the present configuration example, the luminousflux converged by the relay lens 6 is diffused by the first diffusionplate 14 which fluctuates perpendicularly to the optical axis (forexample the vertical direction indicated by the arrow A in FIG. 7).Furthermore, the luminous flux transmitted through the relay lens 10 isdiffused by the second diffusion plate 15 which fluctuatesperpendicularly to the optical axis (for example, the vertical directionindicated by the arrow B in FIG. 7).

FIG. 8 is the third configuration example of the projection displaydevice according to the present embodiment.

The third configuration example illustrated in FIG. 8 is an example ofarranging the first diffusion plate 14 in the position 12 a (or in thevicinity of the position) of the luminous flux emission surface of thethree laser light sources 1, and arranging the second diffusion plate 15in the position 13 b (or in the vicinity of the position) between therelay lens 7 and the relay lens 8. According to the presentconfiguration example, the luminous flux emitted from each of the threelaser light sources 1 is diffused by the first diffusion plate 14 whichfluctuates perpendicularly to the optical axis (for example the verticaldirection indicated by the arrow A in FIG. 8). Furthermore, the luminousflux transmitted through the relay lens 7 is diffused by the seconddiffusion plate 15 which fluctuates perpendicularly to the optical axis(for example, the vertical direction indicated by the arrow B in FIG.8).

FIG. 9 is the fourth configuration example of the projection displaydevice according to the present embodiment.

The fourth configuration example illustrated in FIG. 9 is an example ofarranging the first diffusion plate 14 in the position 12 a (or in thevicinity of the position) of the luminous flux emission surface of thethree laser light sources 1, and arranging the second diffusion plate 15in the position 13 c (or in the vicinity of the position) of theprojection surface of the screen 5. According to the presentconfiguration example, the luminous flux emitted from each of the threelaser light sources 1 is diffused by the first diffusion plate 14 whichfluctuates perpendicularly to the optical axis (for example the verticaldirection indicated by the arrow A in FIG. 9). Furthermore, the luminousflux projected by the projection lens 11 is diffused by the seconddiffusion plate 15 which fluctuates perpendicularly to the optical axis(for example, the vertical direction indicated by the arrow B in FIG.9).

FIG. 10 is the fifth configuration example of the projection displaydevice according to the present embodiment.

The fifth configuration example illustrated in FIG. 10 is an example ofarranging the first diffusion plate 14 in the position 12 a (or in thevicinity of the position) of the luminous flux emission surface of thethree laser light sources 1, and arranging the second diffusion plate 15in the position 13 a (or in the vicinity of the position) of theluminous flux incident surface of the display device 3. According to thepresent configuration example, the luminous flux emitted from each ofthe three laser light sources 1 is diffused by the first diffusion plate14 which fluctuates perpendicularly to the optical axis (for example thevertical direction indicated by the arrow A in FIG. 10). Furthermore,the luminous flux transmitted through the relay lens 10 is diffused bythe second diffusion plate 15 which fluctuates perpendicularly to theoptical axis (for example, the vertical direction indicated by the arrowB in FIG. 10).

In the configuration examples illustrated in FIGS. 6 through 10, theconfiguration examples illustrated in FIGS. 7, 8, and 10 are also theexamples of arranging the first diffusion plate 14 and the seconddiffusion plate 15 in the optical path of the optical system forillumination 2.

Thus, in the projection display device according to the presentembodiment, in the combinations of the arrangement positions of thefirst diffusion plate 14 and the second diffusion plate 15, thearrangement positions can be changed.

With the above-mentioned configuration, the luminous flux from each ofthe three laser light sources 1 is diffused by the first diffusion plate14 and the second diffusion plate 15 in the projection display deviceaccording to the present embodiment. Since at least one of the firstdiffusion plate 14 and the second diffusion plate 15 fluctuatesperpendicularly to the optical axis, the speckle pattern generated whenthe three laser light sources 1 for emitting coherent light are used canbe changed by the diffusing operation of the two diffusion plates. Inaddition, by fluctuating at least one diffusion plate, the luminousfluxes having speckle patterns different with time can be superposed. Asa result, the speckles can be removed almost completely. That is, twodiffusion plates are used, and at least one of them is fluctuated,thereby effectively removing the speckles. Therefore, as compared withthe conventional device having only one diffusion plate, a higherspeckle removing effect can be attained.

The speckle removing effect can be attained by providing the firstdiffusion plate 14 at the light source conjugate position or in thevicinity of the conjugate position, providing the second diffusion plate15 in the display device conjugate position or in the vicinity of theconjugate position, and fluctuating at least one of the first diffusionplate 14 and the second diffusion plate 15 by the ultrasonic motor.Therefore, the speckles can be removed with a simple configuration, anda high quality image can be displayed. Since a configuration of rotatinga diffusion plate is not included, a large device problem does notoccur, and since no optical system for forming on a diffusion plate theimages formed in the illuminated area of the display device 3 isrequired, a large device problem or an increased cost problem does notoccur.

In the projection display device according to the present embodiment, itis desired that at least one of the first diffusion plate 14 and thesecond diffusion plate 15 is an optical diffusion device. The opticaldiffusion device is an optical element which can arbitrarily form adiffusion angle and a luminous intensity distribution form acquired whena luminous flux is transmitted, and which can acquire high uniformityfor a transmitted luminous flux. When a parallel luminous flux istransmitted through the optical diffusion device, the luminous flux canbe diffused like a spherically abraded concave lens by the opticaldiffusion device even though the optical diffusion device is tabular inshape. An optical diffusion device can be, for example, an LSD (lightshaping diffuser) optical element manufactured and sold by Luminit ofthe U.S. It is a parallel flat plate of polycarbonate or acrylicmaterial processed as an LSD surface for diffusing light in a specificrange. The LSD surface has the same effect as a number oftwo-dimensionally arranged microlenses based on the optical refractionwhile a hologram is based on the optical diffraction. An LSD opticalelement can arbitrarily form a luminous intensity distribution formobtained when a luminous flux is transmitted. For example, a luminousintensity distribution form of an oval figure can be generated. It alsohas a high transmittance.

A reflective display device can be used as a display device in theprojection display device according to the present embodiment. Thereflective display device is a device for forming on a projectionsurface an image formed in the illuminated area by reflecting theluminous flux emitted in the illuminated area, and can be, for example,a DMD (digital micromirror device).

Embodiment 2

The projection display device according to the embodiment 2 of thepresent invention displays an image by projecting the image on thescreen, and includes at least one light source, an optical system forillumination, a display device, an optical system for projection, afirst diffusion plate (an example of the first diffusion unit), a seconddiffusion plate (an example of the second diffusion unit), and a rodintegrator (an example of the luminous flux intensity leveling unit).The light source emits coherent light. The optical system forillumination propagates the luminous flux emitted from the light sourceinto a predetermined optical path and leads it toward the screen. Thedisplay device forms an image to be displayed on the screen in theilluminated area illuminated by the luminous flux led by the opticalsystem for illumination. The optical system for projection scales up andprojects the image formed in the illuminated area of the display deviceon the screen. The first diffusion plate diffuses the luminous flux. Thesecond diffusion plate diffuses the luminous flux. The rod integratorlevels the intensity of the luminous flux. The rod integrator isprovided in the optical system for illumination. The first diffusionplate is provided in at least one of the light source conjugate positionand the vicinity of the conjugate positions in the optical path of theoptical system including the light source through the screen. The seconddiffusion plate is provided in at least one of the display deviceconjugate position and the vicinity of the conjugate positions in theoptical path of the optical system. Furthermore, at least one of thefirst diffusion plate and the second diffusion plate fluctuatesperpendicularly to the optical axis. However, the fluctuating diffusionplate fluctuates perpendicularly to the optical axis in the scope of theoptical path of the optical system.

FIG. 11 is a configuration before arranging a first diffusion plate anda second diffusion plate in an example of a configuration of theprojection display device according to the present embodiment.

As described above, in the projection display device according to thepresent embodiment, the first diffusion plate is also provided, as inthe embodiment 1, in at least one of the light source conjugate positionand the vicinity of the conjugate positions in the optical path of theoptical system from the light source through the screen. Likewise, thesecond diffusion plate is provided in at least one of the display deviceconjugate position and the vicinity of the conjugate positions in theoptical path of the optical system, each of the positions being thedisplay device conjugate position or the vicinity. Therefore, there area plurality of combinations of the first diffusion plate and the seconddiffusion plate as arrangement positions. Described below is an exampleof a configuration of the projection display device according to thepresent embodiment excluding the first diffusion plate and the seconddiffusion plate with reference to FIG. 11.

As illustrated in FIG. 11, the projection display device according tothe present embodiment excluding the first diffusion plate and thesecond diffusion plate is different from the configuration exampleillustrated in FIG. 5 in that the relay lens 7 is replaced with a rodintegrator 21, and other configurations are the same as those in FIG. 5.Therefore, the same components as in FIG. 5 are assigned the samereference numerals, and only the rod integrator 21 is described below.

In FIG. 11, the rod integrator 21 is provided in the optical system forillumination 2. The luminous flux incident surface of the rod integrator21 is provided in the position 12 b having a conjugate relationship withthe position 12 a of the luminous flux emission surface of the threelaser light sources 1, that is, the light source conjugate position. Inaddition, the luminous flux emission surface of the rod integrator 21 isprovided in the position 13 b having a conjugate relationship with theposition 13 a of the luminous flux incident surface of the displaydevice 3, that is, the display device conjugate position. The position12 b of the luminous flux incident surface of the rod integrator 21 isalso the converging position by the relay lens 6.

With the above-mentioned configuration example, the positions (lightsource conjugate positions) having conjugate relationships with aposition 12 a of the luminous flux emission surface of the three laserlight sources 1 in the optical path of the optical system including thethree laser light sources 1 through the screen 5 are a position 12 b ofthe luminous flux incident surface of the rod integrator 21, a position12 c of the stop unit 9, and a position 12 d of the entrance pupil ofthe projection lens 11 (refer to the dotted line 12 in FIG. 11). Thepositions (display device conjugate positions) having conjugaterelationships with a position 13 a of the luminous flux incident surfaceof the display device 3 in the optical path of the optical system are aposition 13 b of the luminous flux emission surface of the rodintegrator 21 and a position 13 c of the projection surface of thescreen 5 (refer to the dotted line 13 in FIG. 11).

Therefore, in the projection display device according to the presentembodiment, the arrangement position of the first diffusion plate is oneof the position 12 a of the luminous flux emission surfaces of the threelaser light sources 1 or in the vicinity of the position, the position12 b of the luminous flux incident surface of the rod integrator 21 orin the vicinity of the position, the position 12 c of the stop unit 9 orin the vicinity of the position, and the position 12 d of the entrancepupil of the projection lens 11 or in the vicinity of the position inthe optical path of the optical system including the three laser lightsources 1 through the screen 5. The arrangement position of the seconddiffusion plate is one of the position 13 a of the luminous fluxincident surface of the display device 3 or in the vicinity of theposition, the position 13 b of the luminous flux emission surface of therod integrator 21 or in the vicinity of the position, and the position13 c of the projection surface of the screen 5 or in the vicinity of theposition in the optical path of the optical system including the threelaser light sources 1 through the screen 5.

Thus, in the projection display device according to the presentembodiment, there are a plurality of combinations as the arrangementpositions of the first diffusion plate and the second diffusion plate,but six representative arrangement examples are described below.

In each arrangement example, the first diffusion plate and the seconddiffusion plate are the same as the first diffusion plate 14 and thesecond diffusion plate 15 of the projection display device according tothe embodiment 1, and are assigned the same reference numerals. In eacharrangement example, both of the first diffusion plate and the seconddiffusion plate fluctuate perpendicularly to the optical axis, but theconfiguration in which one of the plates fluctuates can be realized asin the embodiment 1. Each of the first diffusion plate and the seconddiffusion plate is provided with an ultrasonic motor as illustrated inFIG. 18 and described later although not illustrated in the attacheddrawings. The ultrasonic motor can fluctuate the diffusion plate byfinely oscillating a piezoelectric element included in the ultrasonicmotor as in the embodiment 1. The ultrasonic motor for finelyoscillating the piezoelectric element is controlled by a control devicefor controlling the three laser light sources 1 and the display device3. In this case, as in the embodiment 1, the ultrasonic motor iscontrolled so that the fluctuation speed of each of the first diffusionplate 14 and the second diffusion plate 15 can be, for example, 2.0 mm/sor more.

FIG. 12 is the first configuration example of the projection displaydevice according to the present embodiment.

The first configuration example illustrated in FIG. 12 is an example ofarranging a first diffusion plate 14 in the position 12 b (or in thevicinity of the position) of the luminous flux incident surface of therod integrator 21, and arranging a second diffusion plate 15 in theposition 13 b (or in the vicinity of the position) of the luminous fluxemission surface of the rod integrator 21. According to the presentconfiguration example, the luminous flux converged by the relay lens 6is diffused by the first diffusion plate 14 which fluctuatesperpendicularly to the optical axis (for example the vertical directionindicated by the arrow A in FIG. 12). In addition, the intensity of theluminous flux diffused by the first diffusion plate 14 is leveled by therod integrator 21. Furthermore, the luminous flux whose intensity isleveled by the rod integrator 21 is diffused by the second diffusionplate 15 which fluctuates perpendicularly to the optical axis (forexample, the vertical direction indicated by the arrow B in FIG. 12).

FIG. 13 is the second configuration example of the projection displaydevice according to the present embodiment.

The second configuration example illustrated in FIG. 13 is an example ofarranging a first diffusion plate 14 in the position 12 b (or in thevicinity of the position) of the luminous flux incident surface of therod integrator 21, and arranging a second diffusion plate 15 in theposition 13 c (or in the vicinity of the position) of the projectionsurface of the screen 5. According to the present configuration example,the luminous flux converged by the relay lens 6 is diffused by the firstdiffusion plate 14 which fluctuates perpendicularly to the optical axis(for example the vertical direction indicated by the arrow A in FIG.13). In addition, the intensity of the luminous flux diffused by thefirst diffusion plate 14 is leveled by the rod integrator 21.Furthermore, the luminous flux projected by the projection lens 11 isdiffused by the second diffusion plate 15 which fluctuatesperpendicularly to the optical axis (for example, the vertical directionindicated by the arrow B in FIG. 13).

FIG. 14 is the third configuration example of the projection displaydevice according to the present embodiment.

The third configuration example illustrated in FIG. 14 is an example ofarranging a first diffusion plate 14 in the position 12 b (or in thevicinity of the position) of the luminous flux incident surface of therod integrator 21, and arranging a second diffusion plate 15 in theposition 13 a (or in the vicinity of the position) of the luminous fluxincident surface of the display device 3. According to the presentconfiguration example, the luminous flux converged by the relay lens 6is diffused by the first diffusion plate 14 which fluctuatesperpendicularly to the optical axis (for example the vertical directionindicated by the arrow A in FIG. 14). In addition, the intensity of theluminous flux diffused by the first diffusion plate 14 is leveled by therod integrator 21. Furthermore, the luminous flux transmitted throughthe relay lens 10 is diffused by the second diffusion plate 15 whichfluctuates perpendicularly to the optical axis (for example, thevertical direction indicated by the arrow B in FIG. 14).

FIG. 15 is the fourth configuration example of the projection displaydevice according to the present embodiment.

The fourth configuration example illustrated in FIG. 15 is an example ofarranging a first diffusion plate 14 in the position 12 a (or in thevicinity of the position) of the luminous flux emission surface of thethree laser light sources 1, and arranging a second diffusion plate 15in the position 13 b (or in the vicinity of the position) of theluminous flux emission surface of the rod integrator 21. According tothe present configuration example, the luminous flux emitted from eachof the three laser light sources 1 is diffused by the first diffusionplate 14 which fluctuates perpendicularly to the optical axis (forexample the vertical direction indicated by the arrow A in FIG. 15). Inaddition, the intensity of the luminous flux converged by the relay lens6 is leveled by the rod integrator 21. Furthermore, the luminous fluxwhose intensity is leveled by the rod integrator 21 is diffused by thesecond diffusion plate 15 which fluctuates perpendicularly to theoptical axis (for example, the vertical direction indicated by the arrowB in FIG. 15).

FIG. 16 is the fifth configuration example of the projection displaydevice according to the present embodiment.

The fifth configuration example illustrated in FIG. 16 is an example ofarranging a first diffusion plate 14 in the position 12 a (or in thevicinity of the position) of the luminous flux emission surface of thethree laser light sources 1, and arranging a second diffusion plate 15in the position 13 c (or in the vicinity of the position) of theprojection surface of the screen 5. According to the presentconfiguration example, the luminous flux emitted from each of the threelaser light sources 1 is diffused by the first diffusion plate 14 whichfluctuates perpendicularly to the optical axis (for example the verticaldirection indicated by the arrow A in FIG. 16). In addition, theintensity of the luminous flux converged by the relay lens 6 is leveledby the rod integrator 21. Furthermore, the luminous flux projected bythe projection lens 11 is diffused by the second diffusion plate 15which fluctuates perpendicularly to the optical axis (for example, thevertical direction indicated by the arrow B in FIG. 16).

FIG. 17 is the sixth configuration example of the projection displaydevice according to the present embodiment.

The sixth configuration example illustrated in FIG. 17 is an example ofarranging a first diffusion plate 14 in the position 12 a (or in thevicinity of the position) of the luminous flux emission surface of thethree laser light sources 1, and arranging a second diffusion plate 15in the position 13 a (or in the vicinity of the position) of theluminous flux incident surface of the display device 3. According to thepresent configuration example, the luminous flux emitted from each ofthe three laser light sources 1 is diffused by the first diffusion plate14 which fluctuates perpendicularly to the optical axis (for example thevertical direction indicated by the arrow A in FIG. 17). In addition,the intensity of the luminous flux converged by the relay lens 6 isleveled by the rod integrator 21. Furthermore, the luminous fluxtransmitted through the relay lens 10 is diffused by the seconddiffusion plate 15 which fluctuates perpendicularly to the optical axis(for example, the vertical direction indicated by the arrow B in FIG.17).

In the configuration examples illustrated in FIGS. 12 through 17, theconfiguration examples illustrated in FIGS. 12, 14, 15, and 17 are alsoexamples of arranging the first diffusion plate 14 and the seconddiffusion plate 15 in the optical path of the optical system forillumination 2.

Thus, in the projection display device according to the presentembodiment, in the combinations of the arrangement positions of thefirst diffusion plate 14 and the second diffusion plate 15, thearrangement positions can be changed.

With the above-mentioned configuration, it is obvious that theprojection display device according to the present embodiment can obtainan effect similar to the effect of the projection display deviceaccording to the embodiment 1. Furthermore, there is no possibility thatnonuniform illumination occurs on the image projected on the screen 5 bythe effect of leveling the intensity of a luminous flux by the rodintegrator 21.

In the projection display device according to the present embodiment, aswith the projection display device according to the embodiment 1, it isdesired that at least one of the first diffusion plate 14 and the seconddiffusion plate 15 is an optical diffusion device.

Also in the projection display device according to the presentembodiment, it is possible to configure the first diffusion plate 14,the rod integrator 21, and the second diffusion plate 15 in a unitaryconstruction. However, in this case, a fluctuating diffusion plate isconfigured in a unitary construction such that the plate can befluctuated.

In addition, it is possible in the projection display device accordingto the present embodiment that a reflective display device can be usedas a display device. The reflective display device can form on theprojection surface an image formed in the illuminated area by reflectingthe luminous flux illuminating in the illuminated area.

FIG. 18 is an example of a configuration of the projection displaydevice according to the present embodiment using a reflective displaydevice.

As illustrated in FIG. 18, the projection display device includes aslight sources for emitting coherent light a red laser light source 31 r,a green laser light source 31 g, and a blue laser light source 31 b. Thered laser light source 31 r and the blue laser light source 31 b aresemiconductor laser light sources, and the green laser light source 31 gis an SHG (second harmonic generation) laser light source.

After the laser light emitted from the red laser light source 31 r isconverted into parallel luminous fluxes having substantially equaldiameters by a collimator lens 32, it is reflected by a mirror 33, andtransmits through a dichroic mirror 34 and a dichroic mirror 35. Thelaser light emitted from the green laser light source 31 g transmitsthrough a condenser lens 36, and is converted into parallel luminousfluxes having substantially equal diameters by a collimator lens 37,reflected by the dichroic mirror 34, and passes through the dichroicmirror 35. The laser light emitted from the blue laser light source 31 bis converted into parallel luminous fluxes having substantially equaldiameters by the collimator lens 38, and then reflected by the dichroicmirror 35.

The luminous flux transmitted through or reflected by the dichroicmirror 35 is diffused by a first optical diffusion device 39, and entersa rod integrator 40. After the flux repeats the reflection on the mirrorin the rod integrator 40, the flux is emitted from the rod integrator40, and then diffused by a second optical diffusion device 41. In thepresent embodiment, the first optical diffusion device 39 has the entirediffusion angle of 20°. In addition, an ultrasonic motor 52 is fixed viaa frame 51 to each of the first optical diffusion device 39 and thesecond optical diffusion device 41 as illustrated in detail in FIG. 19.By finely oscillating the piezoelectric element included in both or oneof the ultrasonic motors 52, both or one of the first optical diffusiondevice 39 and the second optical diffusion device 41 can be fluctuatedperpendicularly to the optical axis.

After the luminous flux diffused by the second optical diffusion device41 passes through a condenser lens 42 and a filed lens 43, itillustrates a reflective display device 44. The reflective displaydevice 44 is, for example, a DMD. The DMD is provided with a number offine mirrors, and illumination light can be modulated by changing theangle of each mirror depending on an image signal.

The luminous flux illuminating the display device 44 is modulated by thedisplay device 44 according to the image signal, and the modulated lightpasses through the filed lens 43, and scales up by the projection lens45 and projected on the screen 46.

With the above-mentioned configuration, the optical system from thelaser light sources 31 r, 31 g, and 31 b to the display device 44 is anoptical system for illumination, and the optical system from the displaydevice 44 to the screen 46 is an optical system for projection.

The position of the luminous flux incident surface of the rod integrator40 and the position of the entrance pupil of the projection lens 45 havea conjugate relationship with the position of the luminous flux emissionsurface of each of the laser light sources 31 r, 31 g, and 31 b. Theposition of the luminous flux emission surface of the rod integrator 40and the position of the projection surface of the screen 46 have aconjugate relationship with the position of the luminous flux incidentsurface of the display device 44.

The first optical diffusion device 39 is provided in the position of theluminous flux incident surface of the rod integrator 40 or in thevicinity of the position, and the second optical diffusion device 41 isprovided in the position of the luminous flux emission surface of therod integrator 40 or the in the vicinity of the position. The firstoptical diffusion device 39, the rod integrator 40, and the secondoptical diffusion device 41 can be configured in a unitary construction.However, in this case, the first optical diffusion device 39 and thesecond optical diffusion device 41 are configured in a unitaryconstruction such that they can be fluctuated.

The laser light sources 31 r, 31 g, and 31 b is controlled by a lasercontroller 47, and the laser controller 47 and the display device 44 arecontrolled by a control device 48. Thus, in the projection displaydevice, the control device 48 controls each of the laser light sources31 r, 31 g, and 31 b through the laser controller 47, and controls thedisplay device 44 according to the image signal, thereby displayingcolor images in the color sequence system. In addition, the ultrasonicmotor 52 is controlled also by the control device 48, therebyfluctuating both or one of the first optical diffusion device 39 and thesecond optical diffusion device 41 perpendicularly to the optical axis.

With the projection display device having the above-mentionedconfiguration, in addition to the luminous flux diffusing operation bythe two optical diffusion devices, that is, the first optical diffusiondevice 39 and the second optical diffusion device 41, the fluctuation ofboth or one of the first optical diffusion device 39 and the secondoptical diffusion device 41 can change and superpose a speckle pattern.Therefore, the speckle can be substantially completely removed. As aresult, an image can be projected onto the screen 46 with thedisagreeable speckle for users substantially removed. According to theexperiment by the Applicant, when both of the first optical diffusiondevice 39 and the second optical diffusion device 41 are fluctuated, itis confirmed that the speckle has been 90% removed as compared with thecase in which the first optical diffusion device 39 and the secondoptical diffusion device are not provided. When only one of the firstoptical diffusion device 39 and the second optical diffusion device 41is fluctuated, it is also confirmed that the speckle removing effect issufficiently acquired. In this case, specifically when the secondoptical diffusion device 41 provided in the position of the luminousflux emission surface of the rod integrator 40 or in the vicinity of theposition is fluctuated, it is confirmed that a larger speckle removingeffect can be acquired.

By the luminous flux intensity leveling operation by the rod integrator40, the luminous flux on the luminous flux emission surface of the rodintegrator 40 has a substantially uniform intensity distribution.Therefore, there occurs no uneven illumination on the image projected onthe screen 46. It is desired that the entire diffusion angle of thefirst optical diffusion device 39 is 10° through 40°. Such a diffusionangle is desired because the frequency of optical reflection becomes lowin the rod integrator 40 if the diffusion angle is set as an angle lowerthan 10°, thereby acquiring insufficient uniformity in optical intensitydistribution, and incurs uneven illumination on the image projected onthe screen 46. In addition, if the diffusion angle is set as an anglelarger than 40°, the diffusion angle of the luminous flux from theluminous flux emission surface of the rod integrator 40 becomes large,the light cannot be efficiently used, and there is the possibility thatsufficient luminance cannot be acquired on the image projected on thescreen 46.

The applicant made an experiment on the speckle removing effectdepending on the fluctuation speed of the first optical diffusion device39 or second optical diffusion device 41. The result of the experimentis described below.

However, the speckle contrast Cs is defined as follows.

Cs=σ/I

where σ is a standard deviation of the luminous flux intensity, and I isan average value of the luminous flux intensity.

When the first optical diffusion device 39 is fluctuated, and the secondoptical diffusion device 41 is not fluctuated, the speckle contrast ofthe following result is acquired for the fluctuation speed of the firstoptical diffusion device 39.

fluctuation speed Cs 0.0 mm/s 9.5% 0.5 mm/s 6.0% 1.0 mm/s 5.0% 2.0 mm/s4.5%

On the other hand, when the second optical diffusion device 41 isfluctuated and the first optical diffusion device 39 is not fluctuated,the speckle contrast of the following result is acquired for thefluctuation speed of the second optical diffusion device 41.

fluctuation speed Cs 0.0 mm/s 9.5% 0.5 mm/s 6.0%

The 9.5% Cs at the fluctuation speed of 0.0 mm/s indicates that Cs is9.5% when the first optical diffusion device 39 and the second opticaldiffusion device 41 are not fluctuated.

Thus, from the result of the experiment performed by the applicant, itis confirmed that the speckle can be removed more effectively byfluctuating a least one of the first optical diffusion device 39 and thesecond optical diffusion device 41. In addition, since it can beconfirmed that the speckle contrast decreases when the fluctuation speedis increased, it is preferable that the fluctuation speed is, forexample, 2.0 mm/s or more.

The embodiments 1 and 2 are described above. In the projection displaydevice according to each of the embodiments, the diffusion plate or theoptical diffusion device fluctuates perpendicularly to the optical axisby the ultrasonic motor, but it is obvious that other fluctuating unitscan be used.

FIG. 20 is an explanatory view of another example of a fluctuating unit.

In this example, the first optical diffusion device 39 is fluctuated.

The fluctuating unit illustrated in FIG. 20 fluctuates the first opticaldiffusion device 39 by allowing the first optical diffusion device 39 toperform a circular movement. In the configuration, the point on a disc61 rotating on an axis 61 a as a rotation axis by a motor etc. isconnected to one end portion 39 a on one diagonal line of the firstoptical diffusion device 39 as a pivot of the circular movement. Anotherend portion 39 b is fixed to a rail unit 62 which can be slidhorizontally and vertically (perpendicular to an optical axis). Thus, byrotating the disc 61 by a motor etc., the first optical diffusion device39 fluctuates as drawing a circle perpendicularly to the optical axis.In this case, the motor etc. is controlled by the above-mentionedcontrol device. With the configuration, the speckle removing effectsimilar to that described above can be acquired. Also with theconfiguration, the first optical diffusion device 39 does not rotate as,for example, illustrated in FIGS. 2 and 3, thereby preventing a largerdevice.

The present invention has been described above in detail, but thepresent invention is not limited to the embodiments above, and it isobvious that various improvements and alterations can be made within thescope of the gist of the present invention.

As described above, according to the present invention, the projectiondisplay device can efficiently remove speckle substantially completelywith a simple configuration, and display a high-quality image.

1. A projection display device which displays an image by projecting theimage on a screen, comprising: at least one light source outputtingcoherent light; a display device forming an image to be displayed on thescreen in an area illuminated by a luminous flux from the light source;a first diffusion unit diffusing the luminous flux; and a seconddiffusion unit diffusing the luminous flux, wherein: the first diffusionunit is provided in at least one of a light source conjugate positionand the vicinity of the position in an optical path of an optical systemincluding the light source through the screen; the second diffusion unitis provided in at least one of a display device conjugate position andthe vicinity of the position in the optical path of the optical system;and at least one of the first diffusion unit and the second diffusionunit fluctuates perpendicularly to an optical axis.
 2. The deviceaccording to claim 1, wherein: an optical system including the lightsource through the screen comprises: an optical system for illuminationpropagating the luminous flux emitted from the light source into apredetermined optical path and leading the luminous flux toward thescreen; and an optical system for projection scaling up and projectingthe image formed in the illuminated area of the display device; thedisplay device forms an image to be displayed on the screen in the areailluminated by the luminous flux lead by the optical system forillumination; the first diffusion unit is provided in at least one ofthe light source conjugate position and the vicinity of the conjugateposition in the optical path of the optical system for illumination; andthe second diffusion unit is provided in at least one of the displaydevice conjugate position and the vicinity of the conjugate position inthe optical path of the optical system for illumination.
 3. The deviceaccording to claim 2, further comprising a luminous flux intensityleveling unit leveling intensity of a luminous flux, wherein: theluminous flux intensity leveling unit is provided in the optical systemfor illumination, a luminous flux incident surface of the luminous fluxintensity leveling unit has a conjugate relationship with the lightsource, a luminous flux emission surface of the luminous flux intensityleveling unit has a conjugate relationship with the display device; thefirst diffusion unit is provided in the position of the luminous fluxincident surface or the vicinity of the position; and the seconddiffusion unit is provided in the position of the luminous flux emissionsurface or the vicinity of the position.
 4. A projection display devicewhich displays an image by projecting the image on a screen, comprising:at least one light source outputting coherent light; an optical systemfor illumination propagating a luminous flux emitted from the lightsource into a predetermined optical path and leading the luminous fluxtoward the screen; a display device forming an image to be displayed onthe screen in an area illuminated by a luminous flux led by the opticalsystem for illumination; an optical system for projection scaling up andprojecting the image formed in the illuminated area of the displaydevice; a first diffusion unit diffusing a luminous flux; a seconddiffusion unit diffusing a luminous flux; and a luminous flux intensityleveling unit leveling intensity of the luminous flux, wherein: theluminous flux intensity leveling unit is provided in the optical systemfor illumination; the first diffusion unit is provided in a position ofa luminous flux incident surface of the luminous flux intensity levelingunit or vicinity of the luminous flux incident surface; the seconddiffusion unit is provided in a position of a luminous flux emissionsurface of the luminous flux intensity leveling unit or vicinity of theluminous flux emission surface; and at least one of the first diffusionunit and the second diffusion unit fluctuates perpendicularly to anoptical axis.
 5. The device according to claim 1, wherein at least oneof the first diffusion unit and the second diffusion unit is an opticaldiffusion device capable of arbitrarily forming a diffusion angle and aluminous intensity distribution form acquired when a luminous flux istransmitted.
 6. The device according to claim 4, wherein at least one ofthe first diffusion unit and the second diffusion unit is an opticaldiffusion device capable of arbitrarily forming a diffusion angle and aluminous intensity distribution form acquired when a luminous flux istransmitted.
 7. The device according to claim 5, wherein the diffusionangle of the optical diffusion device is 10° through 40°.
 8. The deviceaccording to claim 6, wherein the diffusion angle of the opticaldiffusion device is 10° through 40°.
 9. The device according to claim 1,further comprising a fluctuating unit perpendicularly fluctuating atleast one of the first diffusion unit and the second diffusion unit toan optical axis.
 10. The device according to claim 4, further comprisinga fluctuating unit perpendicularly fluctuating at least one of the firstdiffusion unit and the second diffusion unit to an optical axis.
 11. Thedevice according to claim 9, wherein the fluctuating unit comprises apiezoelectric element.
 12. The device according to claim 10, wherein thefluctuating unit comprises a piezoelectric element.
 13. The deviceaccording to claim 1, wherein a fluctuation speed when at least one ofthe first diffusion unit and the second diffusion unit fluctuatesperpendicularly to an optical axis is 2.0 mm/s or more.
 14. The deviceaccording to claim 4, wherein a fluctuation speed when at least one ofthe first diffusion unit and the second diffusion unit fluctuatesperpendicularly to an optical axis is 2.0 mm/s or more.
 15. The deviceaccording to claim 1, wherein the display device reflects a luminousflux and forms an image.
 16. The device according to claim 4, whereinthe display device reflects a luminous flux and forms an image.
 17. Thedevice according to claim 1, wherein the display device transmits aluminous flux and forms an image.
 18. The device according to claim 4,wherein the display device transmits a luminous flux and forms an image.19. The device according to claim 3, wherein the luminous flux intensityleveling unit, the first diffusion unit and the second diffusion unitare configured in a unitary construction.
 20. The device according toclaim 4, wherein the luminous flux intensity leveling unit, the firstdiffusion unit and the second diffusion unit are configured in a unitaryconstruction.
 21. The device according to claim 3, wherein the luminousflux intensity leveling unit is a rod integrator.
 22. The deviceaccording to claim 4, wherein the luminous flux intensity leveling unitis a rod integrator.